<template>
  <div class="goods-image">
    <!-- 大图 -->
    <div  v-show="show" class="large" :style="[{backgroundImage: `url(${images[currIndex]})`},largePosition]"></div>
    <!-- 中图 -->
    <div class="middle" ref="target">
      <img :src="images[currIndex]" alt="">
      <!-- 黑色遮罩 -->
      <div class="layer" v-show="show" :style="layerPosition"></div>
    </div>
    <!-- 小图 -->
    <ul class="small">
      <li :class="{active: i === currIndex}" v-for="(img, i) in images" :key="i">
        <img @mousemove="currIndex = i" :src="img" alt="">
      </li>
    </ul>
  </div>
</template>

<script>
import { reactive, ref, watch } from 'vue'
import { useMouseInElement } from '@vueuse/core'
export default {
  name: 'GoodsImage',
  props: {
    images: {
      type: Array,
      default: () => []
    }
  },
  setup (props) {
    // 当前图片的索引值
    const currIndex = ref(0)

    // 是否显示遮罩和大图
    const show = ref(false)

    // 大图定位显示的位置样式 后面赋值给dom元素样式
    const largePosition = reactive({
      backgroundPositionX: 0,
      backgroundPositionY: 0
    })

    // 遮罩的坐标样式 后面赋值给dom元素样式
    const layerPosition = reactive({
      left: 0,
      top: 0
    })

    // 使用ref标记需要使用useMouseInElement的DOM元素
    const target = ref(null)

    const { elementX, elementY, isOutside } = useMouseInElement(target)

    // 使用侦听器监听鼠标在中图内容的位置是否发生改变，有的话执行以下代码
    watch([elementX, elementY, isOutside], (newVal) => {
      // 根据得到的数据设置样式数据和是否显示数据
      show.value = !isOutside.value

      // 计算坐标
      const position = { x: 0, y: 0 }

      if (elementX.value < 100) position.x = 0
      else if (elementX.value > 300) position.x = 200
      else position.x = elementX.value - 100

      if (elementY.value < 100) position.y = 0
      else if (elementY.value > 300) position.y = 200
      else position.y = elementY.value - 100

      layerPosition.left = position.x + 'px'
      layerPosition.top = position.y + 'px'
      largePosition.backgroundPositionX = -2 * position.x + 'px'
      largePosition.backgroundPositionY = -2 * position.y + 'px'
    })
    return { currIndex, target, show, largePosition, layerPosition }
  }
}
</script>

<style lang="less" scoped>
.goods-image {
  width: 480px;
  height: 400px;
  position: relative;
  display: flex;
  z-index: 500;
  .middle {
    width: 400px;
    height: 400px;
    position: relative;
    cursor: move;
    .layer {
      width: 200px;
      height: 200px;
      background: rgba(0, 0, 0, 0.2);
      position: absolute;
      left: 0;
      top: 0;
    }
  }
  .small {
    width: 80px;
    li {
      width: 68px;
      height: 68px;
      margin-left: 12px;
      margin-bottom: 15px;
      cursor: pointer; // 设置鼠标形状
      &:hover,&.active {
        border: 2px solid @xtxColor;
      }
    }
  }
  .large {
    position: absolute;
    top: 0;
    left: 412px;
    width: 400px;
    height: 400px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    background-repeat: no-repeat;
    background-size: 800px 800px;
    background-color: #f8f8f8;
  }
}
</style>
